Electric train signaling system



Mardi 7, 1933. p, Nl BOSSART 1,900,405

ELECTRIC TRAIN SIGNALTNG SYSTEM 1 Fi1ed Apri1 2, 1951 2 sheets-sheet lTolZQf'eiUl'ngAp/Uafazas faggi. if

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ELECTRIC TRAIN SIGNALING SYSTEM I Fj.led April 2, 1931 2 Sheets-Sheet 2High Fmgaefzeg 5j T Il" l Aylmer 4.9 1 59'61 1A f6? 4? l L -4k4w 46| Ir45 "lzpulep Sending L26 In e g'o mlepgne.

, INVENTOR.' FV `P,/\/.73o.s'scf/ftl ATTORNEY.

P. N. BoissART 1,900,405

Patented 7, 1933 UNITED STATES PATENT OFFICE PAUL N. BOSSART, OFSWISSVALE, PENNSYLVANIA, ASSIGNOR T THE UNION SWITCH & SIGNAL COMPANY,0F SWISSVALE, PENNSYLVANIA, A CORIORATION 0F PENNA SYLVANIA.

ELECTRIC TRAIN SIGNALING SYSTEM' Application led April 2,

My invention relates to communication systems for railway trains, andparticularly to that class of systems for causing an auX- iliary brakecontrolling mechanism located at some point on the train outside of thelocomotive to register with the position of the usual engineers brakevalve on the locomotive.

I will describe `certain forms of apparatus embodying my invention, andwill then point trol system embodying my invention. Fig.

t is a diagrammatic view of a preferred form of apparatus to be addedtothe receiving equipment of Fig. 2 when it is used with the equipmentof Fig. 3 for the control of the train brakes. In each of the severalviews, like referencecharacters designate like parts.

In electric train signaling systems, it is proposed to confine thesignaling current to frequencies ranging from two thousand to fivethousand cycles per second, with a channel every three hundred cycles.This range will thus give eleven carrier frequency chan' nels.Furthermore, it has been proposed toprovide a definite signal bymodulating the carrier current by a predetermined low frequency, forexample, a modulating frequency of ten to ninety cycles per second.

In signal systems for controlling the train brakes, it is necessary toinsure that the apparatus on one train will not be influenced by thesignaling'currents being generated on some nearby train. To this end, itbecomes necessary to have available a large number of non-interferingcommunicating channels. lVhere the carrier frequency range is set asextending from two thousand to five thousand cycles per second and wherethe modulated frequency range is limited 1931. Serial No. 527,124.

from say ten to ninety cycles per second, `and as reliability requiresat least a three hundred cycle separation of the carrier frequencies andat least a twenty percent separation between modulating frequencies, themaximum possible number of communication channels is found to be elevencarrier frequency channels and thirteen modulating frequency channels orone hundred fortythree communication channels.

As there are five independent brake functions, namely: release, running,lap, service and emergency, there are required at least four separatesignal currents for each train, it being possible to obtain one functionin response to no current. It is evident therefore that the possible onehundred fortythree channels mentioned above will likely not besuflicient to provide all the trains that will approach each otherfromtime to time as they travel over the road with a separate channelfor each brake function.v

If two modulation frequencies are used in combination in place of aseparate modulation frequency for each signal then the thirteen possiblemodulation channels will provide seventy-eight different modulationgroups. These groups combined with the eleven carrier frequency channelsmake possible eight hundred fty-eight communicating channels forsignaling. Applying this idea of a combination of plurality ofmodulation frequencies for each individual signal to the case wheremultiple functions are desired for a system, it is evident that a largenumber of 'non-interfering systems can be provided. Take forillustration, the lcontrol of the train brakes of a given train wherefive separate functions are required by a group of three modulationfrequencies. The five functions may be obtained by using the followingcombination: (first function) modulation 1 and 2; (second function)modulation 1 and 3: (third. function) modulation 2 and 8; (fourthfunction) modulation 1,` 2 and 3; (fifth function) none. It will benoted that in such a combination, no modulation frequency is' usedsingularly. If, for instance, l

two of the functions, such as service and emergency might be combined,thenthe combination would not be re uired.

lcarrier frequencies available, two hundred and thirty-one communicationsystems of five functions each can be provided.

.With the above arrangement, it would be possible for a nearby train onthe same carrier frequency to supply the third modulation frequency toeffect a false change of functions from a pair of frequencies to the12-3 combination. This would of course be a, very rare occurrence. Bymaking the 1-2-3 combination correspond to a lap condition of the brakesystem, no undesirable active function could be initiated on'a train bysome nearby train. If this objection is considered serious, fourmodulation frequencies can be used in groups of three with nocombination of three repeating and since for each group of fourmodulations, four separate groups of three can beobtained, and if thefifth function can be obtained with no current, then there would be noneed of using a 1 2- combination. In such a scheme there is nopossibility of a nearbytrain setting up afalse function of the brakesystem. Furthermore, a still larger number of communicating systems canbe obtained when four modulation frequencies are used in combination.Referring to Fig. 1, there is shown the sending equipment for a carrierfrequency current modulated simultaneously with two lower frequencieslIn' this instance, the e uipment is arranged after the well-knowneisings modulation scheme. The tube TG with its associated circuitssupply the carrier frequency current while the tubes M1 and M2 supplythe two lower modulation frequencies, Each of the three tubes contains afilament 10, grid 11 and plate 12. The grid 11 of the tube TG isprovided with a circuit including a condenser 14 and .a portion of theoscillating coil 15. The current to heat each filament 10 is supplied bythe battery 13, the filaments of the lthree tubes being connected inlparallel. The plate potential for all three tubes is supplied by thebattery 17 through the ordinary Heising iron core reactance coil 18 ofrelatively high impedance to all three frequencies generated. Theoscillating circuit which includes coil 15 and the condenserlrisconnectyed to the plate circuit of the tube -TG through 'the plateblocking condenser 19 -while a portionof the coil 15 is included in thegrid circuit as mentioned above. The characteristics ofthe condenser 16determine the frequency of the carrier current generated. The

Ylow frequency oscillator M1.

grid circuit for a grid leak circuit which inclu es a resistance 32 andan armature 27 of a sending key 26 to be shortly described.

The sending key 26 is mechanic-ally1 connected .to the armatures 27, 28,29, 30 and 31 as indicated by a dotted line. With the key 26 depressedthen each of these armatures engages a respective back contact as willbe apparent from an inspection of the Fig. 1. Whenever key 26 is notdepressed, it returns to its positionas shown in the ligure where eacharmature breaks contact with its back contact and the armatures 30 and31 engage respective front contacts.

Y The control of the electron tubes here shown as eected by opening thegrid leak circu'it may be in some cases better accomplished by openingthe direct current supply to the plate; or by removinga short circuitfrom -a resistor, which then' carries the uw tube 'reis rovided withplate current of the tube and which is so connected in the circuit thatthe voltage drop across it is used to apply a sufficiently largenegative bias to the grid to stop any oscillations of the electron tube.These methods are all well known in the art and the form shown willserve to illustrate thediferent ways by which the electron tubes may becontrolled.

The output coil 20 is inductively coupled with the oscillating coil 15.The coil 2() is connected to the'output circuit which iii-,-

cludes a condenser '21, back contact of armature 31 when key 26 isdepressed, coils 22 and 23 located in inductive relation with the railsl and 11, respectively, coil 24 located in inductive relation with thetrain coupler 25 at the sending location, and a back contact of thearmature 30. The characteristics of the condenser 21 are such as to tunethe output circuit to resonance at the carrier frequency generated bythe tube TG.

The circuits associated with the tube M1 are similar to the circuitsassociated with the tube T11. The oscillating coil 33 vis provided withan iron core and the charac.- teristics of the condenser 34 determinethe modulation frequency generated. 35 is the plate blocking condenser,36 the grid circuit condenser and 38 is a high frequency choke coilwhich prevents the carrier frequency from being by-passed to groundthrough the The grld circuit for M1 is' provided with a grid leakcircuit that includes the resistance 37 and the back contact of armature28 of the sending key 26. The circuits associated with the tube M2 arejust the same as those for tube M1 with the exception that the condenser39 has different characteristics to insure that the modulation frequencygenerated by the oscillator M1 is different than that generated by 1. Itis here pointed out that by providing the high frequency choke coils 3Sand 40 for the tubes M1 and M2 respectively and by plactaneously at twofrequencies will Q of the train.

ing them in the separate plate circuits the impedance of both highfrequency choke coils add to oppose any by-passing of one modulationfrequency through the tube and circuits supplying the other modulationfrequency.

Normally the inductors 22, 23 and 24 are connected tothe receivingapparatus through the front contacts of the armatures and 3l of the key26. Also normally the grid leak circuit for each of the tubes is openwith the result that normallynone of the tube' circuits will oscillateand no signaling current is generated. i'

When key 26 is depressed, all three grid leak circuits will becompleted, all three oscillators will start oscillating simultaneouslyand the coils 22, 23 and 24 will be connected to the output coil 20.v Itfollows then that normally the sending equipment of Fig. l is inactiveand that by depressing the key 26, a carrier frequency current modulatedsimulbe supplied to the track rails 1 and 1a and to the coupler Fig. 2shows the receiving equipment necessary to receive at some other pointon the train, the signals supplied to the traffic rails and traincoupler by the equipment of Fig. 1. In Fig. 2, the parts 4l, 42 and 43are simi q lar in everyrespect to the coils 22, 23 and 24 respectivelyof Fig. l. Likewise the sending key 26 of Fig. 2 is similar to thesending key 26 of Fig. l and normally the coils 41, 42 and 43 areconnected through the front contacts of the armatures 30 and 31 of key26 to the input filter through a condenser 44 which tunes the inputcircuit to resonance at the carrier frequency of the generator TG ofFig. l. The signaling current received by the coils 41, 42 and 43 isapplied through the input filter 45 and a high frequency amplifier 46 tothe rectifier 47 where it is demodulated and the two modulationfrequencies supplied -to the primary 48 of a transformer 49.

While this input filter and high frequency amplifier may take manyforms, ay preferred device is that disclosed and claimed in my copendingapplication for Letters Patent, Serial No. 431085, filed Februaryy 25,v1930.

.As the input filter and amplifier form no part of this invention, it isdeemed sufficient to indicate such apparatus in the Fig. 2 by a symbolin order'to not unduly complicate the drawings.

The secondary 50 of the transformer 49 supplies the circuit for the grid51of'a tube 52 through a biasing battery 53. The filament of the tube 52is constantly heated by a battery 54 and its plate circuit is suppliedfrom a battery 55 through aA relatively high impedance coil 56 in serieswiththe primary 57 of a transformer T. A large by-p`ass condenser.58 isconnectedbetween the filament and the junction point of the coil 56 andbe used to supply current to the high however. to the rectifier-.47,this current is a pulsating direct current which has a varying componentfor each of the two modula tion frequencies of the carrier current. Thispulsating direct current in 'the primary 48 of transformer 49 induces analternating electromotive force in the secondary 50 which has acomponent corresponding to each of the modulation frequencies and thisalternating electromot-ive force is impressed across the grid 51 andfilament of the tube 52. As a result` the plate current of tube 52 isperiodicallyv varied in accordance with the components corresponding tothe two modulation frequencies.

The transformer T has two secondaries 59 .and 60 which supply sharplytuned resonant circuits 1A and 1B, respectively. The circuit 1A indetail includes the secondary 59 and a condenser 61 in series with a low,power factor reactor 62. A full-wave rectifier 63 is connected acrossapart of the reactor 62 and the output of this rectifier 63 energizesthe relay 64. The characteristics of the elements of this 1A circuit aresuch that the circuitis sharply tuned to resonance at one ofthemodulation frequencies of the carrier current. Let us say that thiscircuit 1A responds to the frequency generated by the tube M1 of Fig. 1.It vfollows then that the presence of this modulation frequency in thecarrier current effects the 4energization of the relay1 64.

The 1B circuit includes the secondary 60 and a condenser 6 6 in serieswith a low power factor reactor 67. A full-wave rectifier 68 isconnected acrossa portion of the reactor 67 while the output circuit ofthe rectifier 68 includes. the relay 69. Thecharacteristics of theelements of the 1B circuit are such that it is sharply tuned toresonance at the second modulation frequency of the signaling current.That is to say, it responds to the presence of the modulation frequencysupplied by the tube M2 of Fig. 1 and that the relay 69 is energized asthe result. In case the relaysv64 and 69 are too slow4 in operation dueto being normally short-circuited by their respective rectifier, theresistancesl 65 andv 70 may be inserted in series with the coils of the.relays 64 and 69, respectively.,

'carrier frequency,

as shown in the Fig. 2, although such resistances arenot essential.

Thus to adjust the receiving apparatus of Fig. 2 to any iven channel,condenser 44 and the input lter 45, are adjusted to the secondarycircuit 1A is adusted to one modulation frequency and the secondarycircuit 1B to the other modulation frequency.

It is apparent from the foregoin that as long as the track rails are su.plie with a signaling current of a carrier requency and two modulationfrequencies corresponding to that at which the receiving apparatus ofFig. 2 is adjusted, the two relays 64 and 69 lare both energized. vWhenthe su ply of this signaling current'is discontinue or when the carriercurrent is not modulated then the relays 64 and 69 become deenergized.en both relays are energized a signal here shown as a vibrating bell 71is produced by means of the circuit which includes battery 72, frontcontacts 73 and 74 of relays 64 and 69, respectively, and the bell 71.Thus with one location on a train equipped with the signaling apparatusof Fig. 1 and a second location on the train equipped with the receivingapparatus of Fig. 2, a signal can be transmitted from the rst locationto the second location. Furthermore, if each location on the train isprovided with the equipment of Figs. 1 and 2, communication can beestablished between the two locations by the alternate'openng andclosing of the sending keys. As a matter of fact, one set of sending.and receiving equipment may be located along the trackway with inductorcoils placed in inductive relation to the track rails and communicationestablished between this wayside station anda train traveling on saidtrack. Such a signal system disclosed in Figs. 1 and 2 lpossesses a highdegree of sensitivity and selectivity and is substantially immuneto'shock excitation.

Fig. 3 shows my invention applied to a 'system for the control of trainbrakes by controlling an auxiliary mechanism capable of reproducing thefunctions of the usual engineers brake valve 0n the locomotive and whichmechanism is located at another point on the train. While this secondpoint may be at any location on the train, it will be considered in thisdescription as being in the caboose. In this instance, three lowfrequency generators which I shall ldesignate A, B and-C are provided.The choice of any pair or of three or of none is effected by theposition of the handle 75 of the engineers brake valve EV. v

`As here shown, the low frequency generators are of the electron- .tubetype ,and their associated circuits are of the well-known Hartley director series fed type where the plate voltage is supplied between the plateand the grid coils. For example, coils 97A gages 91 and 92.

and 98A of the iron core oscillator coil 99A are respectively the gridand plate coils of generator A and are closely coupled to each other.100A is the oscillating circuit condenser the characteristics of whichdetermine the frequency delivered by the generator A. 101A is the gridcondenser and 102A is the grid leak resistance. The battery 103 suppliescurrent to the filaments of each of the tubes 104A, 104B and 104Cin'parallel while the plate voltage for all three of the tubes issupplied b the battery 105 by-passed by a large con enser 106.Oscillation of these three low frequency'generators 1s controlled byopening and closing the grid leak circuit the same as previouslydescribed in Fig. 1. The selection of the grid leak circuits-will now betaken up.

As shown schematically, the contact members 76, 77 and 78 areoperatively connected to and actuated by the handle 75 of the engineersvalve EV. Each contact member is adapted to engage a series ofstationary contacts as the handle 75 is moved to the several operatingpositions of the brake valve EV. For example, with the handle 75 inrunning position, the contact member 76 engages no stationary contacts,the contact member 77 engages the stationary contacts 79 and 80 and thecontact member 78 engages the stationary contacts 81 and 82. lVith thehandle 75 at release position, then contact 76 engages the stationarycontacts 83 and 84, and 78 engages the contacts 85 and 86. When thebrake valve handle 75 is placed in the lap position, the contact member76 engages 87 and 88, 77 engages 89 and 90 and 78 en- When the handle isat the service position, the contact members engage no stationarycontacts but when the handle is in the emergency position 76 engagescontacts 93 and 94 and 77 engages 95 and 96.

Each of the pairs of stationary contacts 83-84, 87-88 and 93-94 whenbridged by the associated contactmember 76 completes the grid leakvcircuit for the low frequency generator A. Each of the pair of contacts79-80, 89-90 and 95-96 when bridged by Y the associated contact member77 completes the grid leak circuit for the generator B. Likewise each ofthe pair of contacts 855-86, 81-82, and"9192 when bridgedby the contactmember 78 completes the grid leak circuit for the generator C.

It follows then that with the handle 75 at release osition, generators Aand C are active; w en handle 75 is at running position, generatorsB andCare active; at lap position, all three generators A, B and C areactive; at service position none are active; while in the emergencyposition A and B are active. Thus A and C are used for release, B and Cfor running, A, B and C for lap, none for service, and A and B foremergency.

In Fig. 3, there is provided an intermediate amplifier tube for each ofthe low f requency generators. Referring to generator A, its output isapplied to the grid 107 of the amplifier tube 108A in series with a gridbiasing battery 109. The output or plate circuit of the tube 108A issupplied with currentfrom the battery 105 through a primary winding 110of a transformer T1. It follows then that the current generated by Awill be reproduced in the plate circuit of the tube 108A with enlargedamplitudes and that this plate current flows in the primary 110 oftransformer T1. Inlike manner` the amplifier 108B whose plate circuitincludes the primary 111 of transformer T1 is associated `with thegenerator B.- The primary 112 of transformer T1 is included in the platecircuit of the amplifier 108C which is associated with the generator C.A function of these intermediate amplifiers is to completely prevent anyb'y-passing or interference by the energization of one modulationfrequency with .the circuits of another modulation frequency.

The transformer T1 has a secondary wind# ing 117 connected, through abiasing battery 120, to the grid 118 of the modulating tube 119 of themodulator oscillator designated in Fig. 3 as a whole by the referencecharacter G1. In the secondary 117l all three frequencies A, B and Cwill be induced. That is to say, which ever frequencies. are ,activewill be induced depending upon the selection made by the position of theengineers valve EV. It follows that whichever frequency is selected bythe valve EV, there will be a corresponding component in the Voltageapplied to the grid 118 of the modulator tube 119. 121 is the iron coreplate reactance for the modulator oscillator G1. 122 is an additionalplate battery for the tubes 119 and 123 in series with the plate battery105. Battery 1.22 can of course be a separate` battery independent ofthe battery- 105. 124 isvthe usual high frequency choke to keep thecarrier current out of the modulator tube 119. The carrier currentoscillator 123 and its associated circuits are the same aspreviously'described for the tube TG of Fig. 1, 125 being the plateblocking condenser,

126 the oscillating coil, 127 the grid condenser, 128 the grid leakresistance and 129 the oscillating circuit condenser. The filaments ofthe two tubes 119 and 123 are supplied with current from the battery 130in series. o

Th-e output coil 116 is connected to the sending inductfirs 22, 2.3 and2li-through back contacts of the armatures 114 and 115 of the key 26 andthe tuning condenser 113. The coils 22. 23 and 24 of Fig. 3 are similartothe same elements of Fig. 1 and are similarly located. To sum up theoperation of the sending equipment of Fig. 3, the low frequ-encyvoltages generated by A, B and C are the condensess 100A, 100B and 100Cand the carrier frequency determined -by the condenser 129. The outputcircuit is also tuned to the carrier frequency by the condenser 113.

Fig. 4 shows a preferred form of the receiving apparatus for a trainbrake system to cooperate with the sending apparatus of Fig. 3 in so faras the receiving apparatus differs from the receiving apparatus of Fig.2. In Fig. ,4, the receiving apparatus preceding the transformer T is tobe understood as being the same as that disclosed in the Fig. 2. Thetransformer T of Fig. 4 is provided with three secondary circuitsinstead of two as shown in the Fig. 2. The secondary circuits A1, B1 andC1 of Fig. 4 are sharply tuned to the low frequency of the currentsgenerated by A, B and C of Fig. 3 respectively. The circuit A1 consistsof a condenser 131 and a low power factor reactor 132 tuned to respondto the low frequency generated by generator A. A portion of the reactor132 is connected -to the in- 10 put of the rectifier 133 while theoutput of rectifier 133 is connected to the slow-releasing relay 134A.It follows that when the carrier current is modulated by the low fre'-quency current generated by A the relay 105 134A is energized. In asimilar manner,'the secondary circuit B1, adjusted to the low frequencycurrent generated by B, Will energize the relay 134B in response to thepresence of this modulation frequency in the car- 11 rier current. Alsocircuit C1, adjusted to the low frequency current generated by C, willenergize the relav 134C in response to the presence of this modulationfrequency in the carrier current. p

From the foregoing description, it is apparent that relays 134A, 134Band 134C are energized or deenergized in accordance-to the selection ofthe generators A, B and C by vthe position of the engineers brake valve.129 The relays 134A, 134B and 134C may therefore be utilized to controlan auxiliary brake controlling mechanism located at some point on thetrain outside of the locomotive which, as stated above, we shallvconsider as being in the Caboose. U

The Caboose is provided with a main reservoir MR,a feed valve FV andelectropneumatic valves D adapted to reproduce the functions of theengineers valve on the locomagnet motive. It ywill be understood, ofcourse, that the caboose is further provided with a compressor, etc., toinsure a proper supply of air pressure inV the reservoir MR. The valvesDC, DR and DE are each biased to the closed position and are opened whenits associated magnet 135 is energized. The valve Ds is biased to itsopen position and is closed when its associated magnet 135 is'energized. lVhen valve DC is opened, that is, when its 135 is energized,main reservoir MR is connected with the brake pipe BP so that theauxiliary apparatus will then reproduce the condition that exists on thelocomotive when the engineers Valve is in the release position. When thevalve DE is opened, the brake pipe is connected to the feed valveFvthereby reproducing the condition existing on the locomotive when theengineers valve is in the running position. When the valve Ds is opened,that is, when its magnet 135 is'deenergized, the brake pipe is connectedto the atmosphere through a vent of such characteristics as to produce areduction in the brake pipe pressure at substantially the service rateof the usual brake valve to effect a service :pplication of the brakes.When the valve E is opened by its magnet 135 being energlzed, the brakepipe is connected to the atmosphere through a vent of suchcharacteristics as to cause an emergency rate of reduction of brake pipeVpressure and an emergenc application of the brakes. When the va ves DC,DR and DE are all deenergized and valve DS energized, the conditionreproduced by the auxiliary apparatus corresponds to the lap position ofthe engineers brake valve.

The magnets 135 of the several valves are controlled by theslow-releasing relays 134A, 134B and 134C. Assuming the relays to be inthe position as shown in the Fig. 4, that is,l

relay 134A deenergized and both 134B and 134C energized, current issupplied from the battery 136 through magnet 135 of Ds, back contact ofarmature 137 of relay 134A, front contact of armature 138 of relay 134B,front contact of'armature 139 of relay 134C, magnet 135 of DR and backto the battery 136.v

In the event relays 134A and 134C are energized and 134 B deenergized,then the circuit extends from the battery 136 through ma net 135 of DS,front contact of armature 13%,

, back contact of armature 14() of relay 134B,

front contact of armature 141 of relay 134C, magnet 135 of DC and tobattery 136. Again should all three of the relays be energized, thencurrent is supplied to the magnet 135 of DS, front contacts of armatures137, 140 and 142, respectivel and to the battery 136. Or, in the eventre ays 134A and 134B are energized and relay 134C deenergized, thencurrent is supplied to the magnet 135 of Ds and the magnet 135 of DEthrough the front contact of armatures 137, 140, and back contact ofarmatu're 142. The magnet 135 of the service valve D'J is adapted to beenergized in series with each of the remaining magnets and energizedalone when all three of the relays are energized. This arrangement ofservice valve Ds insures the auxiliary apparatus to operate on theclosed circuit prnciple as any failure of the-apparatus in the caboosewill result in the service valve Ds being deenergized to effect aserviceapplication of the brakes.

In describing the operation of the apparatus of Figs. 3 and 4, let usfirst assume' that the engineers brake valve EV is in its normal runningposition as shown in Fig. 3, and that the key 26 of Fig. 3 is depressedto its sending condition. The B and C generators are rendered active bythe closing of their. respective grid leak circuits and the carrierfrequency current is modulated by the B and C low frequencies. currentis applied to the rails by the sending apparatus and is picked up by theinductors of theA receiving apparatus at the caboose and the relays 134Band 134C energized. With relays 134B and 134C picked up, then the valvesDs and DR are energized-to effect a running condition of the auxiliarybrake mechanism. Let us next assume that the engineers valve is placedat release position, the key 26 still being depressed to its sendingposition. With handle at release position, generators A and C areselected and the carrier current supplied lto the traiic rails will bemodulated by the frequencies of A and C. With a carrier current of A andC frequency modulation picked up by the receiving apparatus at thecaboose, the relays 134A and 134C are energized. With this set-up of therelays in the caboose, the valves DS and DC are energized to effect arelease condition of the auxiliary mechanism. Again in the event thehandle 75 is at lap position and all three generators A, B and Crendered active, all three relays 134A, 134B and 134C in the caboose areselected and the valve Dg only energized, effecting thereby a lapcondition of the auxiliary brake mechanism. Once again let us assumethat the engineers valve is placed in its the generators A, B and C madeactive. In the caboose, all of the relays will be deenergized and theauxiliary mechanism set to effect a service application. of the brakes.In the case the engineers valve is placed at `emergency position Wheregenerators A and B are Selected, the relays 134A and 134B in the cabooseare selected to energize the valves Dsl and DE to render thereby anemergency application of the brakes by theauxiliary mechanism'.

It is apparent from the foregoing descrip- This modulated carrier tionthat the auxiliary brake mechanism in the caboose is adapted toreproduce the several operating functions of the engineers brake valveand that by means of the sending apparatus of Fig. 3 and the receivingapparatus of Figs. 2 and 4, the auxiliary mechanism is made to registerwith the position of the engineers brake valve.

It has been proposed for systems that provide for the control of trainbrakes by an auxiliary mechanism located in the Caboose as Well as bythe usual engineers brake valve that a return indication be sent by theauxiliary mechanism in the caboose to the locomotive, so that thelocomotive driver may know Whether or not the condition that he has setup on the locomotive is being duplicated in the eaboose. Thisrequirement necessitates the providing of a transmitting apparatus inthe caboose and a receiving apparatus on the locomotive. Furthermore, ithas been proposed for systems of this kind'` that there be alternateperiods for sending the control and for the return of the indication.The relays 134A, 134B and 134C of Fig. 4 are made slow-releasing, sothat when supplied With an energizing impulse during each controlperiod, they will retain their armatures in the energized positionduring the indication period. By an alternate movement of a key 26between its sending and receiving positions, then the inductor coilswill be alternately connected to the sending and receiving apparatus.Thus by equipping both the locomotive and the caboose with both thesending and receiving apparatus of my system, a control of the auxiliarybrake mechanism and a return indication to a locomotive can be obtained.

lVhile in this description, definite ranges of frequencies for thecarrier current and for the modulation current have been established, itis to be understood that my invention is not limited to any definiterange of frequencies and that this range of frequencies is given by Wayof'illustration. A system of brake control such as here disclosedprovides a large number of non-interfering channels assuring thereby nointerference between neighboring trains and it provides a system that ishighly sensitive and reliable foreach individual train.

Although I have herein shown and described only certain forms ofapparatus embodying my invention, it is understood that various changesand modifications may be made therein Within the scope of the appendedclaims Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. In combination, a railway train, a brake controlling mechanism havinga plurality of operating functions, a transmitting means capable ofsupplying a carrier frequency current simultaneously modulatedbypdiiferent groups of low frequency currents, means for establishingthe frequency of the carrier current and the frequencies of each of themodulating currents of the transmitting means of the train, a manuallyoperated device adapted to select a different group of the modulatingcurrents for each of the different operatmg functions of the brakemechanism, a recelving means responsive to the modulated carrier currentsuppliedlby the transmitting means for causing the operating function ofthe brake mechanism to register withthat selected by the manuallyoperated means, and selecting means to adjust said receiving means torespond to the current supplied by the transmitting means of that trainand none other.

2. In combination, a signaling mechanism having a plurality of operatingconditions, a transmitting means capable of supplying a carrierfrequency current simultaneously modulated by different groups of lowfrequency currents, means for establishing the frequency of the carriercurrent and the frequencies of each of the modulating currents of thetransmitting means, a manually operated device adapted to select adifferent grou of modulating currents for each of the differentoperating conditions of the signaling mechanism, a receiving meansresponsive to the modulated carrier current supplied by the transmittingmeans for causing the operating condition of the signaling mechanism toregister With that selected by the manually operated device, andselecting means to adjust said receiving means to respond to the currentsupplied by said transmitting means and none other.

3. In combination, a railway train, a brake controllingmechanism havinga plurality of operating functions, a transmitting means capable ofsupplying a carrier frequency current simultaneously modulated bydifferent groups of low frequency currents, a manually operated meansadapted to select a different group of the modulatingcurrents for eachof the different operating functions of the brake mechanism, a receivingmeans responsive to the modulated carrier current supplied by thetransmitting means for causing the operating function of thebrake mech--uiism to register vyith that selected bythe manually operated means.

4. Apparatus for the control of theseveral operating functions of trainbrakes comprising in combination, a source of carrier c urrent on thelocomotive, means for simultaneously modulating said carrier currentWith different groups of alternating current of different frequencies,-a manually operated device on the locomotive for selecting a differentgroup of modulating currents for each operating function of the trainbrakes, a brake controlling mechanism located on the train at a pointoutside the locomotive capable of producing the several operatingfunctions of the brakes,and a receiving and demodulating meansassociated With the brake controlling mechanism selectively responsiveto the several groups of modulating frequencies of the carrier currentvfor causing the condition of the said brake controlling mechanism toregister Awith the manually controlled device on the locomotive.

- 5. Apparatus for the control of train brakes comprising in combinationwith the usual engineers brake valve on the locomotive, a source ofcarrier current, means for simultaneously modulating said carriercurrent with different groups of alternating currents of differentfrequencies, means for selecting a different group of modulatingcurrents for each position of Vthe engineers valve, auxiliary brakecontrolling mechanism at another point on'the train capable ofreproducing the functions of the engineers valve, and a receiving anddemodulating means associated with said auxiliary mechanism selectivelyresponsive to the several groups of modulating frequencies of thecarrier current for causing the condition of the auxiliary mechanism toregister with the position of the engineers valve.

6. Apparatus for the control of train brakes comprising in combinationwith the usual engineers brake valve on the locomotive, a source ofcarrier frequency current, means for simultaneously modulating saidcarrier current with different groups of alternating currents, means forselecting a different group of modulating alternating currents for eachposition of the engineers valve,'

auxiliary brake controlling mechanism at another point on the traincapable of` reproducing the functions of the engineers'valve, and

receivlng and demodulating means associated with said auxiliarymechanism selectively responsive to the several groups of `modulatingcurrents of the carrier current for causing the condition of theauxiliary mechanism to register with the'position of the engineersvalve. A

7. Apparatus for the control of train brakes comprising in combinationwith the usual engineers brake valve on the locomotive, a transmittingmeans capable of supplying a carrier frequency current simultaneouslymodulated by different groups of low frequency currents, means fordetermining the frequency of the carrier current and the frequencies ofthe modulating currents, means operatedby the engineers brake valve toselect a different group of modulating currents for each of theoperating positions of the engineers valve, auxiliary brake controllingmechanism at another point on the train capable of reproducing thefunctions of the engineers valve, receiving means associated with saidauxiliary mechanism responsive to the `current supplied by saidtransmitting means for causmg the .condition of the auxiliary mechanismto register with the position of the engineers valve, and selectingmeahs to adjust said receiving means to respond to the current suppliedby the said transmittingA means and to none other.

8. In combination, a railway having a plurality of railway trains, abrake controlling mechanism for each train having a plurality ofoperating functions; a non-interfering control system for the control ofthe brake controlling mechanism of each train including, a generatingmeans to supply a carrier frequency current simultaneously modulated bya group of different low frequency currents for each operating functionof the brake mechanism, and a selectin means adapted to establish thefrequencies o the currents supplied and capable of providing fordifferent frequencies for the different trains; a manually operatedmeans to select the different groups of modulating frequencies for thedifferent operating functions of the brake controlling mechanism of atrain.

and a receiving means on the train influenced by the modulated carriercurrent for causing the brake mechanism to establish'the operatigfunction corresponding to that selected by the manually operated means.

9. In combination, a railway having a plurality of railway trains, asignaling mecha-y nism for each train having a plurality of conditions;a non-interfering control system for the control of the signalingmechanism of leach train including, a generating means to supply acarrier current simultaneously modulated by a different group ofcurrents for eachA condition 'of the signal ing mechanism, and aselecting means adapted to `establish the frequency of the carriercurrent and of each of the modulating currents, and capable ofarrangement for different frequencies for each train; means to selectthe different groups of modulating currents for the different conditionsof the signaling mechanism of a train, and a receiving means on thetrain influenced by the modulated carrier current forcausing thecondition of the signalingmechanismtoregister with that selected by saidlast mentioned means.

10. In combination, a railway having a. plurality of railway trains. asignaling mechanism for each train having a plurality of conditions; anon-interfering control system for the control of the signalingmechanism of each train including, a generating means to supply acarrier.current simultaneously impressed by a different group ofmodulators for each-condition of the si naling mechanism, and aselecting means a apted to estab# lish the characteristics of thecarrier current and of each of the modulators, and capable ofarrangement for different characteristics for 'each train; means toselect the different groups of modulators for the different con-Y llO bythe modulated carrier current for causing the condition of the signalingmechanism to register with that selected by said last mentioned means.

11. In combination, a railway having a plurality of railway trains, asignaling mechanism foreach train having four conditions; anon-interfering control system for the control of the signalingmechanism of each train including, a generating means to supply acarrier current simultaneously modulated by the three diiferent pairs offrequencies obtainable from a group of three modulatingl frequencies forthree conditions and modu ated by no frequency for the fourth conditionof the signaling mechanism, and a. selecting means to establish thefrequency of the carrier current and of each of the modulatin currentsand capabe of arrangement for di erent frequencies of the carriercurrent and that the said group of three modulation frequencies beingchosen for different trains so that no two frequencies of any group arecommon to two or more trains having the same frequency of carriercurrent; means to select the different pairs of the modulating currentsfor the different conditions of the signaling mechanism of a train, anda receiving means on a train iniuenced by the modulated carrier currentfor causing the condition of the signaling mechanism to register withthat selectedl by the last mentioned means.

12. In combination, an output circuit, an electron tube generator ofcarrier frequency current normally inactive, a plurality of electrontube generators of modulation current each normally inactive, a normallyopen grid leak circuit for each of said generators, means tosimultaneously close said grid leak circuits to render said generators-active to supply the output circuitwith a carrier currentsimultaneously modulated by a plurality of modulating currents, and asignaling device controlled by said output circuit.

13. Apparatus for the control of train brakes comprisingin combinationwith the usual engineers brake valve on the locomotive, an auxiliarybrake controlling mechanism locatedat another point on the'train yadapted to reproduce the operating functions of the engineers valve,anelectron tube generator of carrier .frequency current, a plurality ofelectron tube generators of modulating currents, a transmitting circuit,a normally open grid leak circuit for eachof the generators ofmodulating current, means for closing a diiierent group of grid leakcircuits for each position of the engineers valve to supply thetransmitting circuit with a carrier current simultaneously modulated bya different group of modulating currents for each position oftheengineers valve, and a receiving and demodulating means responsive tothe current supplied by the transmit-ting circuitfor causing theauxiliary mechanism to.

register with the position of the engineers valve. Y

14. A. control system including, a transmitting circuit, a generator ofcarr1er frequency current, a plurality of generators of modulatingfrequency currents of different frequencies, a first control means toselectively control the modulating currents to determine the modulatingfrequencies of the carrier current, a second control means to controlthe output of the generator of carrier current to determine the periodwhen said transmitting circuit is supplied with modulated carriercurrent, and signaling circuits iniiuenced by said modulated carriercurrent selectively responsive to the' different modulating frequencies.i

15. A control system including,means located at one pointfor generatinga carrier frequency current, a plurality' of generators of modulatingfrequency current each havinga distinctive frequency, means forrendering different groups of thev generators of modulating currentactive to simultaneously modulate the carrier current, receiv ing anddemodulating apparatus located at another point adaptable to receivesaid modulated carrier current, a plurality of con- -trolling devicesgoverned by said ,receiving and demodulating apparatus each responsiveto a distinctive one of the modulating frequencies, and a plurality ofsignaling devices controlled by the controlling devices and selectivelyresponsive to groups of said modulating currents.y

16. A control system including, a source of carrier` frequency current,a plurality of modulators each having a distinctive frequency, means forrendering different groups of said modulators active to modulate thecarrier current simultaneously to form different control currents,receiving and demodulating apparatus adaptable to be iniuenced by themodulated carrier current, a plurality of controlling devices governedby said receiving and demodulating apparatus each responsive to thefrequency of a specific modulator, and signaling devices controlled bythe controlling devices and selectively responsive to the differentgroups of modulating frequencies for establishing a distinctive signalfor each control current.

17. A control system including, a source of carrier frequency current atone location, a pluralit of modulators each havin a distinctiverequency, control means different positions for rendering differentgroups of said modulators active to modulate the different aving thecarrier current simultaneously to form .i

plurality of controlling relays governed by said receiving apparatuseach res onsive to the frequency o a s ecilc modu ator, and operatingcircuits seiectively controlled by the controlling relavs in accordancewith the different groups o modulating frequencies of the controlcurrents for establishing the condition of the operating mechanismcorresponding to the position of the control means.

18. Apparatus for the control of train brakes comprising in combinationwith the usual engineers brake valve on the locomotive, a source ofcarrier frequency current, means rendered eii'ective for a given brakecondition of the engineers brake valve to simultaneously modulate thecarrier current by a. group of different modulating frequencies, anauxiliary brake controlling mechanism at another point on the traincapable of reproducing said given condition of the engineers brakevalve, receiving and demodulating means at said other point adapted toreceive the modulated carrier current,

and means governed by the receiving and demodulating means selectivelyresponsive to said group of modulating frequencies for causin theauxiliary mechanism to establish said given brake condition.

In testimony whereof I aix my signature.

PAUL N. BOSSART.

